In F1 2021, it can rain at any circuit, not just those that you associate with wet races. That means you'll have to be as prepared for the heavens opening as much at Spa as you will be in Bahrain. This is also the case for the United States GP, where you'll need to adapt your dry setup for wet weather.
The Circuit of the Americas did see a wet race back in 2015, so these conditions aren't unheard of. We've put in the hours in practice perfecting our setup so you don't have to. Here's the best wet setup we found for Austin.
Aerodynamics
There are two long straights in the USA and low wings angles will help down these. However, you'll need high wing angles for COTA, thanks to the high-speed Esses which make up the first sector and the long corners in the final sectors. We found that 8-10 was best for Austin, as this keeps the rear of the car planted to the tarmac.
Transmission
In wet conditions, you have to have a transmission that's more towards the open side. This is to allow for a smoother transmission of power when you're getting back on the throttle and for a stable ride through long corners like the esses section.
65% on-throttle differential allows you to be confident in traction zones. 50% off-throttle diff keeps the car stable when you're off the accelerator going through the esses and other long corners like Turns 16-18.
Suspension Geometry
The wet weather tyres are very durable in F1 2021, so your camber and toe values can be low to allow for more grip. The minimum toe values of 0.05 and 0.20 are best, as they give you maximum grip.
The cambers can't be as adventurous, you can go all the way to the top with -2.50 on the front. You can't get away with the same on the rear though, in the aim of tyre preservation. -1.70 on the rear is what we've found to be best.
Suspension
The suspension springs need to be on the soft side for COTA. This is because you'll need to be using the kerbs through sections like the esses. The car will need to be planted through these corners, you can't afford to have a snappy ride. We've found 3-4 for the suspension is ideal for Austin.
The suspension does have to be weighted towards a responsive car though, as the anti-roll bar will see you through high-speed direction changes. 7-7 is what is best for the USA, as this gives great turn-in without making the rear axle get away from you.
Finally, the ride height has to be on the high side. This is thanks in part to the sharp incline towards Turn 1. However, it's also down to the kerbs, as a low ride height would end with you spinning out if you use them. 4-7 is what we found to be ideal.
Brakes
There are some big stops around COTA, with Turn 12 being the main overtaking spot. Therefore, you need to crank up the brake pressure to 95% to have a chance to pass into that and spots like Turn 1. As for the brake bias, you're best having this around 56% towards the front.
Tyres
Like with the suspension geometry, you can be liberal with the tyre pressures in the wet at COTA. Tyre wear isn't an issue here, especially for the rears, which you can set to the maximum pressure of 23.5 psi. This is to help maintain tyre pressures in long flat-out runs like the backstraight.
For the fronts, overheating can be an issue, so this is ideal at around 23.0 psi.